EPA’s Office of Air and Radiation has requested advice and review to help in developing an integrated plan for conducting the science, risk-exposure, and policy assessments that will provide the basis for EPA's decisions on the national ambient air quality standards for particulate matter.

Under the Clean Air Act, EPA is required to carry out a periodic review and revision, as appropriate, of the air quality criteria and the primary and secondary standards for six criteria air pollutants, which include particulate matter. Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings.